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AssigneeShell Oil Company
InventorsGregory L. Johnson, Norman C. Samish, Diana M. Altrichter
Estimating the term…
A regeneration zone for fluid catalytic cracking contains ammonia (NH.sub.3) when the regeneration zone is operated in a partial combustion mode as defined by a content of CO of between 1 and 6 percent by volume. If the ammonia is not removed from the regeneration zone off gass, the same will be passed to a CO combustion zone where, in the presence of oxygen, CO is oxidized to CO.sub.2 and some of the ammonia will undesirably be oxidized to NO.sub.x. This invention reduces the presence of ammonia in the feed gas to a CO combustion zone of an FCC process by the introduction of a NO.sub.x -containing gas to dilute phase of a regeneration zone or to a regeneration zone off gas. Ammonia, NO.sub.x and oxygen present in the regeneration zone off gas of the regeneration zone, will tend to react to produce nitrogen and water vapor, which then is passed to the CO combustion zone for CO oxidation to CO.sub.2. Where the addition of NO.sub.x is made at temperatures greater than 1700.degree. F., hydroxyl precursor addition may not be required. Where addition is made at temperatures lower than 1700.degree. F. a hydroxyl precursor may be added to the gas admixtures.
A process to reduce NO.sub.x content in a CO combustion zone effluent stream of a fluid catalytic cracking process having a regeneration zone operated in a partial mode of combustion wherein said regeneration zone contains from 1 to 6 volume percent CO which comprises combining a regeneration zone off gas stream containing CO, CO.sub.2, HCN and NH.sub.3 with an additive gas stream comprising a substantially stoichiometric quantity of NO.sub.x compared to the quantity of NH.sub.3 in said off gas stream, to form a combined gas stream, passing said combined gas stream to said CO combustion zone in which an oxygen-containing gas is added for the combustion of CO to CO.sub.2 and to form said combustion zone effluent stream, wherein the content of NO.sub.x in said combustion zone effluent stream is reduced as a result of the reaction of said NH.sub.3 with said added NO.sub.x prior to entry of said combined gas stream to said combustion zone.
A process for the reduction of NO.sub.x emissions from a fluid catalytic cracking regeneration zone operated in a partial mode of combustion wherein said regeneration zone contains from 1 to 6 volume percent CO to form CO, CO.sub.2, O.sub.2, HCN, and NH.sub.3 in said flue gas, which process comprises combining said flue gas with an additive gas stream comprised of NO.sub.x and maintaining said admixture for a period of time sufficient to permit said NH.sub.3, O.sub.2, and NO.sub.x to combine to form H.sub.2 O and N.sub.2.
In a process to reduce NO.sub.x emissions in a fluid catalyst regeneration zone effluent gas derived from a catalyst regeneration zone of a fluid catalytic cracking process, wherein said zone is operated in a partial combustion mode wherein said regeneration zone contains from about 1 to 6 volume percent CO to form said effluent gas comprising spent catalyst, CO.sub.2, N.sub.2, H.sub.2 O, from about 1 percent to about 6 percent CO, O.sub.2, HCN, and from 10 ppm to 10,000 ppm NH.sub.3 which comprises:
Dependencies are inferred from the claim text.